1. Technical Field
The present invention relates to a light source device and a projector.
2. Related Art
There has been used a projector for modulating a light beam irradiated from a light source in accordance with image information to and project an optical image in an enlarged manner.
As a light source device of the projector as described above, there has also been known a arrangement having a discharge type light source lamp such as a metal halide lamp and a high pressure mercury lamp, a reflector for reflecting a light beam irradiated from the light source lamp, and a sub-reflection mirror for reflecting the light beam irradiated forward from the light source lamp toward a side of the reflector (see, for instance, Document: JP-A-2005-148293).
Meanwhile, when the sub-reflection mirror is mounted to the light source lamp like the light source device disclosed in Document, temperature of the light source lamp tends to be high as compared to an arrangement in which no sub-reflection mirror is provided, because, for example, the light source lamp is affected by heat generated in the sub-reflection mirror by the light beam irradiated thereto and because radiation of heat generated in the light source lamp is restricted by the sub-reflection mirror. More specifically, the temperature of the light source lamp on a side on which the sub-reflection mirror is mounted becomes higher than temperature on a side opposite to the side on which the sub-reflection mirror is mounted, which causes temperature distribution of the light source lamp to be biased. When cooling is reinforced by forced cooling or the like to lower the temperature of the light source lamp, temperature of the side opposite to the side on which the sub-reflection mirror is mounted may lowered more than necessary and may cause a so-called blackening phenomenon by which an evaporated electrode material adheres to an inner wall of the light source lamp (a light-emitting tube). The blackening phenomenon described above may induce a drop of illuminance or breakdown of the light source lamp.
Accordingly, a technique has been desired to prolong a life of the light source device by reducing the bias of the temperature distribution of the light source lamp and avoiding the drop of illuminance and breakdown of the light source lamp in the arrangement in which the sub-reflection mirror is mounted to the light source lamp.